Device for monitoring the planar displacement of a continuous web



Ma 1970 c. AKE G. WASTESSON 0 DEVICE FOR MONITORING THE PLANARDISPLACEMENT OF A CONTINUOUS WEB Filed June 23, 1966 IN V EN TOR. C an?A Kc Gusmv Wastes son qua mummy.

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United States Patent US. Cl. 250219 6 Claims ABSTRACT OF THE DISCLOSUREThe invention provides a device for sensing the planar displacement of acontinuous web comprising in combination at least two beam-emittingmeans and a corresponding number of beam-receiving means locatedadjacent one edge of said web, each of said beam-receiving means beingpositioned to receive signals along a straight line path from thecorresponding beam-emitting means, each of said beam-emitting means andthe corresponding beam-receiving means being positioned on oppositesides of the main plane of said web and also on opposite sides of aplane coinciding with one edge of said Web and being at right angles tosaid main plane, whereby a predetermined upward movement of said webcauses only one of said beam-receiving means to receive a beam, and apredetermined downward movement of said web causes the other of saidbeam-receiving means to receive a beam. The device may be adjusted toalso sense the continuity of the web by positioning the correspondingbeam-emitting means and beam-receiving means so that the straight lineconnecting each of said corresponding emitting and receiving meanspasses through the web when it is in its usual planar position.

The present invention relates to a device for sensing a web such as apaper web by means of an emitter such as a light or ultrasonic sourceand a detector (receiver) which is provided to receive signals from theemitter along the connecting line between the emitter and the detector.In known devices of the kind under consideration said connecting lineextends at right angles to the web and is located inside of the one sideedge of the web. The web will thus shield-off the signals to thedetector until the web breaks.

A disadvantage of the known sensing device is that there is noindication of the height position of the web which may be of interest inorder to determine the strain in the web and in order to indicate anypossible fluttering of the web.

The object of the present invention is to provide a device of the kindunder consideration which will sense breakage of the Web and also theheight position of the web Within a greater or smaller range. This willbe obtained by means of a device which according to the invention hasthe features indicated in the annexed claims. According to the inventionthe operative signal beam will thus be obliquely directed towards thesurface of the web and may be so disposed that the beam will hit thedetector when the side edge of the web has been moved upwardly beyond apredetermined position or downwardly below a predetermined position,respectively. Preferably, two de- Vices according to the invention areemployed in combination with each other, one of said devices beingprovided to create a signal when the edge of the web is passing below apredetermined lower limit position whereas the other device is providedto create a signal when the web passes upwardly beyond a predeterminedupper limit position. Seen in the direction of movement of the web thetwo beams will cross each other and the edge of the web 3,501,642Patented Mar. 17, 1970 will be able to move up and down in a rangebetween the beams. Depending on the distance of the edge of the Web fromthe crossing point of the beams there will be obtained a greater orsmaller range between the beams for moving the side edge of the web in avertical direction. By means of the device according to the invention itwill be possible to immediately observe an undue slackening of the webat a certain position along the web which slackening normally proceeds abreakage at another position of the web. The driving means of the webmay accordingly be stopped upon breakage or before due to the fact thatthe impulses from the detector or the detectors are so coupled that theyat a predetermined reduced strain in the web and a slackening resultedtherefrom will stop the driving means of the web. In certain cases theweb will be subjected to vibration or violent oscillation and these willalso be sensed by means of the device according to the invention.Furthermore, there is obtained a certain control of the position of theweb in the transverse direction. Preferably, a device according to theinvention is placed at each side of the web.

A preferred embodiment of the invention is shown by way of example inthe annexed drawing.

FIG. 1 shows diagrammatically a device according to the invention havingtwo emitters and two detectors, the device being seen in the directionof movement of the web, FIG. 2 is a view from above of the device inFIG. 1, and FIG. 3 is a diagrammatic perspective view of the device inFIGS. 1 and 2.

Reference numeral 1 denotes a paper web which, furthermore, is shown intwo positions 1a and 1b indicated by dotted lines. The position 1aindicates an upper limit position and the position 1b indicates a lowerlimit position.

At the side edge 2 of the web is provided a coupling box 3 which on itsside facing the web is provided with two shielding-off devices in theform of two parallel pipes 4 and 5 which are located at differentheights and are displaced relative each other in the longitudinaldirection of the web. At their outer end portions the pipes 4, 5 areprovided with small slit-shaped openings 6, 7 on their sides facing theweb.

On the front side of the box 3 are furthermore provided two lamps 8, 9which form light sources to throw a light beam 10 and 11, respectively,into the openings 7 and 6, respectively, the wall of the pipe around theopening being provided to shield-off any other light from the lamps.When the beams reach the openings 6, 7 unobstructed they will hit thedetector located within the pipe which may be in the form of photo cells12 and 13, respectively. Instead of the light sources 8, 9 it ispossible to use an ultrasonic emitter, and corresponding detectors 12,13 would in this case merely receive signals along the lines 10, 11.

In the intermediate position indicated in FIG. 1 by a solid line for theweb 1, the side edge 2 of the web will extend into the path of signallines 10, 11 so that the signals to the detectors 12, 13 areshielded-off by the edge portion of the web. Since the device of FIG. 1is symmetrically constructed seen in the longitudinal direction of theweb the lines 10, 11 will cross each other in a point 14. The web 1will'pass through this point 14 in its intermediate position and willextend somewhat beyond this point. Depending on the distance of the sideedge 2 from the point 14 the side edge may be moved upwardly ordownwardly within a greater or lesser range before the edge passes theone or the other of the lines 10, 11. If the edge 2 is positionedfurther inwardly toward coupling box 3, that is at a greater distancefrom the point 14, it may move upwardly and downwardly within a greaterrange between the lines 10, 11 before any signal will reach thedetectors 12, 13.

From FIG. 1 it will be seen that the devicewill also sense displacementsin a transverse direction of the edge 2.

Preferably, two devices of the kind shown in FIG. 1 are employed and areplaced at each side edge of the web 1. Accordingly, there will also beobtained a very accurate control of the movement of the web in atransverse direction. A plurality of devices according to the inventionmay be placed along the length of the web so that on a central controldesk it will be possible to observe any changes of the web atpredetermined places between the various stations for the treatment ofthe web. The device shown is primarily intended for paper webs forprinting of newspapers but Webs of any other material may advantageouslybe controlled by means of the sensing device according to the invention.

What I claim is:

1. A device for sensing the planar displacement of a continuous webcomprising in combination at least two beam-emitting means and a,corresponding number of beam-receiving means located adjacent one edgeof said web,

each of said beam-receiving means being being positioned to receivesignals along a straight line path from the corresponding beam-emittingmeans, each of said beam-emitting means and the correspondingbeam-receiving means being positioned on opposite sides of the mainplane of said web and also on opposite sides of a plane coinciding withone edge of said web and being at right angles to said main plane,

whereby a predetermined upward movement of said web causes only one ofsaid beam-receiving means to receive a beam, and a predetermineddownward movement of said web causes the other of said beamreceivingmeans to receive a beam.

2. The device of claim l-which also senses the continuity of the webwherein each of said beam-emitting means and the corespondingbeam-receiving means are positioned so that the straight line connectingeach of said corresponding emitting and receiving means passes throughthe continuous web whereby neither of said beamreceiving means receivesa beam while the web is continuous and while it does not have upward ordownward movement above or below said predetermined upward or downwardmovement.

3. The device of claim 2 wherein each of said beamreceiving meansextends from a holder which also contains said beam-emitting means andwhich provides adjustable positioning of said means.

4. The device of claim 2 wherein a pair of beam-emitting means andcorresponding beam-receiving means are located adjacent both edges ofsaid continuous web.

5. The device of claim 2 wherein said beam-emitting means emits lightrays.

6. The device of claim 2 wherein said beam-emitting means are spacedfrom each other in the direction of movement of said web.

References Cited UNITED STATES PATENTS 5/1963 Early 250223 X 5/1963Frommer et a1. 250 219 X US. Cl. X.R. 22620; 250223

